Microsoft is urging people whose computers are running with pirated Windows software to install official Microsoft security patches – and promises not to punish them.

Tens of millions of computer owners are thought to use pirated software, and security experts are concerned that so many computers running with unpatched security issues could help the spread of botnets and viruses.

The problem was highlighted by the recent hacking of Google’s Chinese infrastructure, which was done by exploiting a loophole in Microsoft’s Internet Explorer browser.

Users of pirated Windows software tend to avoid going to Microsoft sites, as Microsoft has been zealous in the past in tracking down computers running bootlegged copies of its products. Microsoft is capable of sending back tracking cookies to computers which check that the software they’re running is the legitimate article. Apart from sending warning notices to the user, it is possible to disable such software remotely, and so shut the computer down.

But Chester Wisniewski, security analyst at Sophos, says users should trust Microsoft on this one, and was supported by a Microsoft spokeswoman interviewed by USA Today.

Jill Lovato said users of pirated software could obtain security updates like legitimate users, via Windows Update or the Download Centre at Microsoft.com.

“We like to work with customers who have non-genuine copies of Windows, and at the same time work to improve the overall health of the Internet by fighting malware. We will continue this path of constructive engagement with our customers,” she said.

Most people who use pirated software (especially OS's) know what they are doing run software which even Microsoft is unable to detect as pirated - as such they use it as a legitimate user would, applying updates and patches.

As for a cookie shutting down or disabling your machine - that's rubbish designed to spook those who don't know what they are doing away from doing it.